The present invention relates generally to a rustication for providing reveal bands in concrete and related precast structural members, and more particularly to an inexpensive, onepiece, reusable rustication made from extruded foam that exhibits improved sealing with a casting surface.
Tiltup (or precast) construction of concrete wall sections is wellknown in the art. In such an approach, forms are placed on a flat casting surface and filled with concrete, which is then cured. Once the concrete has set, the form is removed and the wall or panel is tilted up into a preferred, typically vertical, orientation. In some instances, the casting surface is coated with a release agent to facilitate easy separation between it and the panel. Additional structural reinforcements, such as rebar, can be placed within the form prior to pouring the concrete. Architectural features, such as decorative bands, can also be cast into the panel by including one or more formed rustications adjacent the casting surface. Prior art rustications have been made from wood, plastic or metal, where the plastic and metal parts have been preferred in part due to relatively inexpensive, highly automated extrusion processes, where parts can be formed and easily cut into a desired length.
Unfortunately, cost and manufacturing difficulties persist, notwithstanding the improvements made possible by extruded metal or plastic rustications. To obtain the proper balance of weight and strength, the prior art has had to adopt complex structural schemes, with a concomitant adverse impact on cost. Moreover, prior art rustication still exhibits performance limitations. For example, the tendency of the poured concrete to leak into gaps between the rustication and the casting surface prior to drying and hardening is problematic in that the resulting dried concrete portion that has leaked through can stick to the rustication, which can in turn lead to increased cleanup time and cost. Also, stray pieces of cured concrete, if adhered to the finished panel, can adversely effect its quality. In addition, adhesion between the panel and the rustication can cause the latter to become damaged when a worker attempts to separate the two, thus resulting in an unintended, cost-prohibitive one-time rustication use. Accordingly, the dimensionality of the engaging surfaces between the prior art rustication and casting surface is critical to avoid these gaps. This, in turn, necessitates closer tolerances to ensure surface uniformity, which increases cost.
Accordingly, there exists a need for a rustication device that is inexpensive to manufacture and simple to use. An additional need exists for a rustication that can ensure that tiltup wall panels are precast with a minimum amount of poured concrete seepage or bleed-through, thereby avoiding concrete-chamfer bonding upon curing of the concrete.
The need is met by the present invention, which comprises a rustication used to provide reveal bands in precast and related tiltup wall panels without the disadvantages of the prior art. According to a first embodiment of the present invention, a rustication for preparing reveal bands in the surface of a precast panel is disclosed. The rustication is made from a one piece elongate body of extruded foam, and includes an upper surface, a lower surface and laterally-spaced sidewall surfaces that extend between the upper and lower surfaces to join the two. The lower surface defines a base plane. At least one downward-extending edge extends from the lower surface corner of the rustication base plane. Each edge projects beyond the lower surface such that the majority of the base plane defined by the lower surface would not contact a generally planar panel forming surface absent the application of a downward-acting external load. The cantilever nature of the edge allows it to be flexible enough to deflect under the application of a load, such as when concrete is poured around it to form the precast panel. Under such a load, the edge splays, thus scraping along the top of the panel forming surface so that an enhanced sealing engagement between the panel forming surface and the rustication is effected. In addition, depending on the load, other portions of the lower surface of the rustication can come in contact with the panel forming surface, thereby improving contact between the rustication and the panel forming surface. The outer surface of the rustication body is preferably made up of a skin that is substantially nonporous relative to the core of the body. While to some extent such a nonporous skin can be a natural concomitant to conventional extrusion processes, it is also possible to control skin properties with appropriate extrusion parameters. Please note, however, that details relating to the skin (including its relative density, thickness and method of formation) is not the subject of the present invention. As used in the present disclosure, an outer surface (alternately referred to as an outward-facing surface) of the rustication is any surface that is facing or can be placed in direct contact with the panel forming surface, poured concrete or related precast material. Also as used in conjunction with the present disclosure, the term xe2x80x9csubstantiallyxe2x80x9d refers to an arrangement of elements or features that, while in theory would be expected to exhibit exact correspondence or behavior, may, in practice embody something slightly less than exact For example, in the present context, even if a surface or element did not possess precisely the desired quality, by being xe2x80x9csubstantiallyxe2x80x9d of that quality, its approximation to such quality would be encompassed under the present definition. For example, the edges, while in a preferable configuration are substantially coplanar with the outer surface of the sidewall surfaces, could have a built-in upward concavity or more vertical-projecting normal surface relative to the sidewall surface to improved scaling. In the context of the present invention, a foam piece is to be distinguished over other extruded materials in that it intentionally includes porosity throughout a majority of its structure, whereas most conventional extruded materials (for example, metals and plastics) are either porosity-free or include only residual porosity. It is precisely the advantageous structural, weight, cost and formability properties made possible by the present rustication""s exploitation of foam that renders the benefits described herein.
According to another embodiment of the invention, a rustication for preparing reveal bands in the surface of a precast panel is disclosed. The rustication is made from a one piece elongate body defined by a core section of extruded foam and an outer section. As with the previous embodiment, the outer surface of the rustication body can include a skin that is substantially nonporous relative to the core section. The outer section of the body includes an upper surface, a lower surface defining a base plane and a pair of laterally-spaced sidewall surfaces that each terminate on their respective lower portion with an integral, downward-extending edge. The outward-facing surface of the edge, which is configured to be exposed to poured precast material, is substantially coplanar with the outer surface of the sidewall surface from which it extends. In the present context, an upward-facing surface can include any surface that has a normal projection therefrom that has a Cartesian component thereof that points vertically up. Thus, for example, the sidewall surfaces of a trapezoidal member, although not facing purely vertical, would be xe2x80x9cupward-facingxe2x80x9d. The lower surface is coupled to the upward-facing surface(s), and is configured to have at least a portion thereof engaging a panel-forming surface. The present embodiment can incorporate features similar to that of the previous embodiment.
According to still another embodiment of the invention, a rustication for preparing reveal bands in the surface of a precast panel is disclosed. The rustication is made up of a one piece elongate body of extruded foam, and includes a core section and an outer section. The outer section comprises at least one upward-facing surface, a lower surface defining a base plane with the lower surface coupled to the upward-facing surface, and at least one downward-extending edge that projects below the base plane. Upon formation of the precast panel, the rustication exhibits enhanced sealing engagement with the panel-forming surface, due in part to the one or more downward-extending edges configured to engage a panel forming surface. Preferably, although not necessarily, the present embodiment rustication is triangular-shaped, where the at least one upward-facing surface could be two surfaces that form the upstanding legs of the triangle, with the lower surface forming the triangle base. In addition, the triangle shape can take on numerous forms, depending on the application, including acute, right or obtuse angles at the apex. As with the previous embodiment, the outer section of the rustication body can include a skin that is substantially nonporous relative to the core section.
According to yet another embodiment of the invention, a method of manufacturing a precast panel with a reveal band formed therein is disclosed. The method includes configuring a rustication to include a one piece elongate body of extruded foam, placing the rustication on a panel forming surface, pouring uncured precast material (such as concrete) around the rustication, curing (hardening) the precast material, and removing the rustication from the precast panel. The rustication includes an upper surface, a lower surface defining a base plane, laterally-spaced sidewall surfaces that join the upper and lower surfaces, and at least one downward-extending edge that projects below the base plane such that upon formation of the precast panel, the rustication exhibits enhanced sealing engagement with the panel forming surface. Preferably, the downward-extending edge is substantially coplanar with the laterally-spaced sidewall surface from which it extends. The rustication formed by the present method can have an outer skin be substantially nonporous relative to the porous core, similar to that of the previous embodiments. The rustication is configured to rest upon the panel-forming surface in a predetermined location prior to pouring the uncured precast material. Optionally, the method also includes the step of securing the rustication to the panel-forming surface prior to pouring the precast material to ensure that it does not move under the load of the precast material.
According to still another embodiment of the invention, a method of producing a rustication with a one piece elongate body of extruded foam is disclosed. The method includes configuring an extruder to include an output stream defined by a predetermined shape, providing the extruder with a quantity of foamable material, and operating the extruder such that the foamable material is forced through the output stream in such predetermined shape to form the rustication. The predetermined shape of the output stream includes an upper surface, a lower surface and a plurality of laterally-spaced sidewall surfaces that join between the upper and lower surfaces. Optionally, the method includes the additional step of forming a plurality of apertures in the rustication to enable rustication attachment to the panel forming surface. As with previous embodiments, the outer skin of the rustication formed by the present method can be substantially nonporous relative to the porous core. As an additional optional step, the rustication exiting the extruder can be segmented (such as by cutting) into individual pieces of predetermined length.